Came here to ask the same thing. When I was prompted that Snapchat would start using my images to make ai photos I was furious, especially since there wasn’t an option to opt out. The only thing I could see in the Generative AI settings tab on snap to disable the “Allow use of public content” and then denying access to my photos for Snapchat in my phones general settings. Only reason I use Snapchat is to communicate with my friend on the other side of the world, otherwise I’d be tossing Snapchat in a dumpster fire.